A1708 820-00840-A no power

[hgoncalves]

Hi,

I have an A1708 820-00840-A with no power. Client says that it just stoped working.

With the board alone at the bench, the ampmeter just stays black, and on the bench PSU it pulls 5.06V.

USBC_XA_CC1/2 and USBC_XB_CC1/2 diode reading seams to be ok (0.594).

PP20V_USBC_XA_VBUS_F has 0.522V on F3000, and 0.184 diode reading

PP20V_USBC_XB_VBUS_F has 5.06V on F3010, and 0.184 diode reading

Should i replace U3100?

 

[2informaticos]

Be aware, CC1/2 signals don't go directly to J3300.
Check diode mode on the _CONN side of them.
Also inspect USB-C terminals for corrosion.

 

[hgoncalves]

I can't see any corrosion on USB-C terminals, and all _CONN caps have 0.191 on diode reading

 

[2informaticos]

Compare diode mode readings on other J3300 pins with good board.
Also do the same for CD3215 LDOs.

 

[hgoncalves]

All readings were normal, and after a close look, i realize that U3100 had a small burnt mark on it and so i replaced it.

Now it powers on, but it was not charging, and stoped consuming any amperage after a while. The ampmeter stayed black again, but it worked while on battery.

However, after a PR Reset it started to pull 20V again, 2.98A and is charging the battery again.

Waht should i check to make sure that it is ok?

 

[2informaticos]

Test it 1 day...